1. Field of the Invention
The present invention relates to an apparatus for and a method of designating, with a manual controller, a certain point within a given area having different vertical and horizontal dimensions, such as a polygonal area, an elliptical area, etc. on an image displayed on an image display unit, and a readable recording medium which stores a program for designating a certain point within a given area on an image displayed on an image display unit.
2. Prior Art
Heretofore, images displayed on the display screen of the image display unit of a video game system such as a television game system are controlled in their movement by the game player with a plurality of control switches on a manual controller. Certain video games require the game player to designate a certain point on displayed images. In a video baseball game, for example, it is necessary for the game player to designate a position where the pitcher is to pitch the baseball (hereinafter referred to as a "pitching position"), or a position where the batter is to swing the bat (hereinafter referred to as a "swinging position"). It has been customary for the game player to designate such a position by operating a digital joystick such as a cross key.
When the digital joystick is operated, a contact position thereof which is displayed on the displayed image moves two-dimensionally in four directions to a point where the digital joystick outputs a corresponding positional signal. The contact position based on the positional signal is converted by a coordinate transforming unit into an image position that is expressed as X and Y coordinates with respect to a reference point on the display screen of the image display unit.
When the contact position based on the positional signal is converted into the image position by the coordinate transforming unit, a conversion constant used to convert the contact position into the X coordinate and a conversion constant used to convert the contact position into the Y coordinate are the same as each other. Therefore, the game player of the video baseball game can only designate a pitching position only within a square area on the displayed image though an actual strike zone is displayed as a vertically long rectangular shape on the displayed image. Such limitations have failed to make the video baseball game realistic.
It has been known to designate a position on a displayed image with an analog joystick which is capable of continuously generating two-dimensional coordinates in relation to positions on the displayed image.